I need to know the sizes and thread pitch on some bolts I need.

-Top two tranny bolts through the bell housing into the 4.0 block.

-The 4 bolts that hold the tranny mount to the ax15.

Thanks in advance,
Billy

 

Bellhousing screws: Upper are 3/8"-16, lower are 7/16"-14. Match from the old ones for length underhead, or calculate by adding the thickness of the flange and adding the nominal diameter (then taking the nearest whole quarter-inch, going up if in between lengths.)

Mount screws are probably M8-1.25. Same formula for calculating length as above (if you have 5/16"-18 you can check - if the 5/16"-18 screw feels like it will almost start in the hole, it's M8-1.25 threaded. The two are often confused. If the screw drops right in, it's probably M10-1.5. I do not expect it to be an M6-1.0 thread.)

Once you confirm sizes, would you please let me know? I'm trying to keep a running screw size chart in the Tech section on my site...

 

I know the heads on the top two stock bolts are an 15mm external hex head bolt. Which are junk and a pain to get off.

 

While there is some standard for the wrenching head size in relation to nominal screw diameter, it doesn't always hold (reduced hex, flanged hex, heavy hex, ...)

A 15m/m hex head should be an M10 screw, but not always. Besides, the OEM screws used in the upper bellhousing holes are external Torx (E12, to be specific,) because Torx is more efficient to use in manufacturing - particularly in inaccessible locations.

Those screws are threaded 3/8"-16 - so pull them out, match length, and throw them away. Replaced with Hex Head CapScrews (HHCS) to save yourself a good deal of trouble next time...